GB2338021A

GB2338021A - Water storage system

Info

Publication number: GB2338021A
Application number: GB9812165A
Authority: GB
Inventors: Dick Rombout
Original assignee: Ballast Nedam Grond en Wegen BV
Current assignee: Ballast Nedam Grond en Wegen BV
Priority date: 1996-12-23
Filing date: 1998-06-05
Publication date: 1999-12-08
Anticipated expiration: 2018-06-05
Also published as: DE19756811A1; GB9812165D0; GB2338021B; NL1004876C2

Abstract

A method for controlling the quantity of liquid in the ground, comprises the steps of: - manufacturing separate liquid storage elements 1, wherein these elements each comprise an outer wall which encloses a space with a pre-determined volume, wherein at least one liquid inlet/outlet channel is arranged between the outer wall and the liquid storage area in each element, - transporting a predetermined number of these prefabricated elements to a desired location; and - excavating a site at this location in which a reservoir must be arranged.

Description

2338021 1 METHOD FOR MAKING A RESERVOIR AND RESERVOIR SYSTEM The present

invention relates to a method for making a reservoir and a system for temporarily storing and releasing liquid for a period of time, wherein this liquid is particularly groundwater or surface water.

Rainwater which has fallen on hardened surfaces such as roads and roofs is generally drained to sewage treatment plants for cleaning, whereafter this cleaned water can once again be discharged into the environment.

A problem here is that in general this water is already clean enough to enter the environment directly, without first having to be cleaned in a sewage treatment plant.

Known underground systems have the drawback that they generally consist of individual plates which must be mutually coupled in an already excavated reservoir site in order to construct a system in situ. This is very time-consuming, difficult to perform and entails high cost. Such 'a system is known from W095/16833.

An object of the present invention is to solve one or more of these problems.

According to a first aspect, the present invention provides a method for controlling the quantity of liquid in the ground, comprising the steps of:

- manufacturing separate liquid storage elements, wherein these elements each comprise an outer wall which encloses a space with a pre-determined volume, wherein at least one liquid inlet/outlet channel is arranged between the outer wall and the liquid storage area in each ele- ment, transporting a pre-determined number of these prefabricated elements to a desired location; and - excavating a site at this location in which the reservoir must be arranged.

Since a system according to the present invention does not have to be built up in multiple steps, i.e.

1 1 2 first constructing individual liquid storage elements from manufactured components and subsequently-assembling these components at the reservoir site, a very efficient and rapid method is provided for making a reservoir system with a desired volume. This means that it is very easy to simply place a pre-determined number of elements in a reservoir site in order to provide a reservoir with the desired volume.

Prior to placing, a pre-determined number of storage elements are preferably arranged in a covering in order to optimally hold the number of elements together as a unit.

After placing of the storage elements in a reservoir site, they can be covered with a layer of material such as soil or sand.

Placing of the pre-determined number of storage elements preferably takes place in one movement from outside the excavated reservoir site. This means that operations does not have to be carried out in the loca- tion itself, whereby a very rapid and simple method is provided for making a system.

According to another aspect of the present invention, a system is provided for use in the above stated method, comprising a number of liquid storage elements, wherein each element has a pre-fabricated, completely operational form comprising an outer wall, a space of a pre-determined volume within this outer wall and one or more liquid inlet/outlet channels which run from this space and through this outer wall.

Since liquid, in particular groundwater which pene trates the system according to the present invention, is only stored and is released once again into the environ ment within a determined time period without being sub jected to further process steps, the quantity of water which enters a sewage treatment plant is reduced, wherein less processing is required. Less energy is thus required in the use of these installations, which results in a decrease in processing and installation costs.

As the system consists of a pre-determined number of individual storage elements having in each case a pre 3 fabricated operational form, a flexible system is provided, wherein this system, once it is placed under the ground, can shift with ground movements without significant damage to the system occurring whereby it would no longer be able to operate.

The storage elements preferably have a substantially convex form in order to optimize the storage volume relative to the outer wall surface area of the element and also to create a maximum hollow space between the elements which can be filled by further elements in order to provide a very efficient system construction.

In order to increase stability, two or more elements can be mutually coupled.

The system is preferably connected to a drainage pipe.

In this manner the system can be coupled to existing systems, wherein water which would normally be guided directly to a sewage treatment plant is guided instead to the system according to the present invention.

The system can further be provided with a pre-puri fication unit, for instance a sand and/or leaf collecting unit, to prevent undesired material entering the system whereby the system could possibly become clogged.

According to another aspect of the present inven- tion, there is provided the use of the above stated system as a channel extending substantially downward from the ground surface for connecting a first water level to a second, deeper water level.

According to yet another aspect of the present invention, the above stated system is used to provide a flexible water canal through a box dam, dike or the like.

owing to the flexibility of the system according to the present invention it can be used as a liquid transport system, wherein owing to the relatively light weight of the system a weight-saving is also obtained at for instance a dam, whereby the occurrence of ground settlements caused by the weight of the dam is reduced.

The present invention will now be further described on the basis of the specific description following here- inbelow with reference to the figures, in which:

4 figure 1 shows a top view of a first embodiment of a system according to the present invention; figure 2 shows a side view of the system of figure 1 coupled to one or more house water drainpipes; figure 3 shows a side view of a second embodiment of a system according to the present invention; figure 4 is a top view of the system of figure 3; figure 5 is a side view of a further embodiment of the system according to the present invention with three pre-purification units; figure 6 shows a partly cut-away side view of a third embodiment of the present invention; figure 7 is a side view of a fourth embodiment of the present invention; and is figure 8 shows a preferred embodiment of a liquid storage element according to the present invention.

A system 1 (figure 1) according to the present invention comprises a large number of convex water storage elements in the form of spheres 2 which are received in a covering 4 which is preferably made from waterpermeable tarpaulin-type material, for instance a 10006 polypropylene cloth which also ensures that material which can cause blockages, such as soil and sand, is kept out of the system.

Table 1 below gives technical specifications of preferred covering material, wherein a covering with a weight of 600 g/m' is particularly recommended.

Table 1

Standard technical data NICOFELT unit Weight 9/m2 200 300 400 500 600 800 NF G 38-013 Thickness (2KPa) mm 3 3.5 4 4.5 5 5.8 NF G 38-12 Tensile strength kN/m 6 9.6 14.6 19 23 30 DIN 5385712 N/5cm. 300 480 730 950 1150 1500 Elongation at % 100/80 100/80 100/80 100/80 90/70 90/70 break DIN 5385712 CBR N 800 1300 2000 2600 3200 4400 DIN 54307 Dry sieve test micron 110-90 110-90 100-80 90-70 50-60 80-60 Water permeability m/s >3B0-3 >3E0-3 >3E0-3 >3E0-3 >3E0-3 >2E0-3 "K"-value Spheres 2 have in each case a plurality of inlet/outlet channels 6, whereby water can flow into and leave the spheres. Each sphere 2 thus has its own liquid permeability capacity and water movement capacity.

Spheres 2 are preferably made of synthetic material, which is most preferably recycled plastic material.

Spheres 2 or any part of the system can comprise filter means (not shown) in order to ensure that the system does not become clogged by for instance sand or soil material.

The system 1 is coupled to a water drainpipe 8 which, as shown in figure 2, can form part of a rainwater drainage system of for instance one or a number of houses in a neighbourhood.

Rainwater received in pipe 8 is carried into the system 1, wherein this water is taken up by spheres 2 via 6 inlet channels 6, until all spheres 2 have reached their storage capacity.

This water then sinks into the ground from the channels 6.

If there is an excess of water, water is held in the system until the water level drops again, whereafter the water can once again be released into the environment.

Figure 3 shows a side view of a further embodiment 10 of the system which is applied as a water overflow drain.

A number of spheres 2 are placed in a covering 12 in a pre-dug pit so as to extend from just above the water surface of for instance a lake downward into the ground through water-impermeable strata, for instance clay and a clay-sand mixture, into a water-permeable stratum.

If the water level of the lake rises above the upper edge 12 of system 10 (see also figure 4), this excess water is taken up into the system and transported to the deeper water level, where the water is released.

Figure 5 shows the system 1 coupled to a water discharge conduit 8, a leaf collection unit (not shown) and two sand collection units 14 which must keep leaves respectively sand out of the system.

A box dam 16 (figure 6) has a dam wall 18, behind which a number of spheres 2 are received in a covering 19. In this embodiment of the present invention the spheres 2 can serve as lightweight supply material, with which box dam 16 can be made less heavy. A number of spheres can also be embodied with a closed outer wall, whereby they provide a buoyancy to box dam 16.

A dike 20 (figure 7) is provided with a water channel system 22 consisting of a number of hollow cubeshaped liquid storage elements of a determined size. Figure 7 shows cubes with for instance two different cube sizes 24 respectively 26. Each cube can be covered with a covering (not shown). This system 22 according to the present invention makes it possible to provide a very efficient dike which is reasonably light in weight and wherein an efficient water channel of high stability can be made between the two sides of the dike.

7 Each cube (figure 8c) is provided with a channel 28 extending through the cube, wherein system 22 can be assembled such that these channels of different cubes coincide in order to provide a water conduit.

It will be apparent that, in addition to the above described specific embodiments of the present invention, the system according to the present invention can also be applied as for instance a light supply material with or without buoyancy, an aeration channel in ground cleaning, for aerating flowing water, as underground water discharge channels and water passageways, wherein a "bridge,, is formed by the system through which passage of water from one place to another is possible.

The present invention is not limited to the above described preferred embodiments, the rights applied for being defined by the following claims.

8

Claims

1. Method for controlling the quantity of liquid in the ground, comprising the steps of:

- manufacturing separate liquid storage elements, wherein these elements each comprise an outer wall which encloses a space with a pre-determined volume, wherein at least one liquid inlet/outlet channel is arranged between the outer wall and the liquid storage area in each element, transporting a pre-determined number of these prefabricated elements to a desired location; and - excavating a site at this location in which a reservoir must be arranged.

2. Method as claimed in claim 1, wherein the predetermined number of storage elements is placed in the location in substantially one movement.

3. Method as claimed in claim 1 or 2, wherein, prior to placing, a predetermined number of storage elements are arranged in a covering.

4. Method as claimed in any of the foregoing claims, comprising the further step of covering the reservoir with one layer of material such as soil or sand.

5. Method as claimed in any of the foregoing claims, wherein placing of the pre-determined number of storage elements is carried out from outside the excavated reser- voir site.

6. System for use in a method as claimed in any of the foregoing claims, comprising a number of liquid storage volume elements, wherein each element has a pre fabricated, completely operational form comprising:

- an outer wall; - a space of a pre-determined volume within this outer wall; and - one or more liquid inlet/outlet channels which run from this liquid storage area and through this outer wall.

9 7. System for use in a method as claimed in any of the claims 1-5, comprising a number of liquid storage volume elements, wherein each element consists of two or more connectable volume units, wherein the elements 5 comprise:

8. storage 9. storage ing.

System as claimed in claim 6 or 7, wherein the elements have a substantially convex form. System as claimed in claim 6, 7 or 8, wherein the elements are arranged substantially in a cover- 10. System as claimed in any of the claims 6-9, further comprising connecting members between the storage elements.

11. System as claimed in any of the foregoing claims which is connected to a liquid supply conduit, for instance a water conduit.

12. Use of a system as claimed in any of the claims 6-11, for temporary storage of liquid, particularly groundwater, and subsequent release of this temporarily stored liquid at determined points in time.

13. Use of a system as claimed in any of the claims 6-11 as a channel extending substantially downward from the ground surface for connecting a first water level to a second, deeper water level.

14. Use of a system as claimed in any of the claims 6-11 to provide a flexible water canal through a dam, for instance a box dam, a dike or the like.

15. Dam, in particular a box dam, comprising a system as claimed in any of the claims 6-11, wherein the system is arranged between a first box dam wall and a second box dam wall.

16. Dike comprising a system as claimed in any of the claims 6-11.